1. Field of the Invention
The present invention relates to an operating apparatus of a wireless communication system. More particularly, the present invention relates to an apparatus and method for, if an amount of data from a channel is large, reproducing data comprised of only the minimum amount of valid data from among input data to reduce a buffer size and a hardware design cost, and performing operation processing.
2. Description of the Related Art
A wireless communication system changes a modulation order and an error correction code adaptively to a channel between transmit/receive ends through an Adaptive Modulation and Coding (AMC) technique, thereby promoting an increase in frequency efficiency.
In addition, the wireless communication system promotes an improvement of system throughput by allocating a channel to a Mobile Station (MS), in consideration of channel states between a Base Station (BS) and MSs, through scheduling. For this, there is a need to forward Channel Quality Information (CQI) estimated at a receive end, to a transmit end.
On the other hand, Orthogonal Frequency Division Multiple Access (OFDMA) utilizes a characteristic of a frequency selective channel and applies the AMC and scheduling for each subband. Here, the subband generally represents a unit in which a channel quality characteristic is maintained. In this case, because CQI for each subband has to be forwarded from a receive end to a transmit end, a signaling overhead for CQI forwarding increases and thus, wastes channel resources. In addition, a size of a buffer, used for storing data channel-estimated before performing the CQI, increases.
For example, if each ‘I’ data and ‘Q’ data, which are output data of a channel estimator, is 12 bits, the combined ‘I’ data and ‘Q’ data output through a multiplexer is 24 bits.
At this time, in the case of a 4×2 Multiple Input Multiple Output (MIMO) system, the size of the buffer storing data channel-estimated before performing the CQI is equal to 196608 bits. A channel value must always be maintained and therefore the buffer size is larger than a case of a 2×2 MIMO system.
However, the input data becomes 24 bits multiplexed through two inputs of 12 bits. 8 bits from among the 12 bits of input data are valid data, and the remaining bits are extra data that are used to prepare for a case where a channel change is likely.
Thus, there is a problem that a buffer size of a wireless communication system increases and hardware becomes more complex.